Drainage and other trenches of various sizes and shapes are desirable for a number of applications. For example, manufacturing facilities typically require drainage systems that include trenches formed in the building floors to collect, remove, and/or recycle excess water or other liquids. These trenches may also be used as utility chases to provide temporary or permanent routing of electrical lines, pipes, conduits or the like below the level of the building floor. In addition, numerous outdoor industrial and commercial sites, such as parking lots, also require drainage systems, including trenches, to collect and direct rainwater and other liquids to underground storm sewers to prevent flooding and to decrease run-off. Similarly, roadways and the like may also require drainage systems, including trenches.
In the past, these trenches have generally been formed by first placing and securing a form of predetermined shape in a ditch that has previously been formed in the ground. A moldable trench-forming composition, such as cementitious material, is then poured around the form and is allowed to set. Once the cementitious material has set, the form is removed from the resulting trench.
One type of form assembly used to define a trench includes a wooden form and strut structure. The wooden form includes a wooden frame which is covered with wooden sheets or planks to define a generally rectangular elongated trough. The wooden form is typically enclosed along its side and bottom faces, but may have an open top. Typically, a number of supporting wooden ribs are installed within the wooden form to increase the strength of the form so that it can withstand the relatively large pressures exerted by moldable trench forming compositions poured about it.
The wooden form is placed and secured within a preformed ditch. Cementitious material is typically poured up to the bottom face of the form and allowed to set in order to anchor the wooden form in the ditch. Then, additional cementitious material is poured between the earthen walls of the ditch and the wooden sides of the form. Once all of the cementitious material has set, the wooden form is disassembled and removed from the trench.
Wooden forms are generally formed of lumber having a relatively rough exterior texture. Correspondingly, the inside surface of the trench formed by the wooden form is relatively uneven which reduces the efficiency of the flow of liquid through the trench. In addition, the assembly and disassembly of the wooden forms is both costly and labor intensive. The relatively large cost and labor required for assembly and disassembly of the wooden forms is increased in the formation of long trenches, and even further increased in the formation of trenches having a pitched or slanted bottom surface to facilitate drainage.
Inexpensive forms are employed to form trenches instead of using the wooden forms discussed above. These trench-forming assemblies preferably include opposing longitudinal frame members having a plurality of anchoring rods extending downwardly from the frame members. An elongated form body, preferably formed of relatively lightweight expanded polystyrene, includes aligned longitudinal slots in the opposed side walls for receiving the frame members. Horizontal portions of the frame members are secured within the longitudinal slots in the sidewalls of the form body during formation of the trench so that the frame members are held in alignment during the trench forming operation.
Preferably the assembled form and frame members are placed into a prepared ditch by suspending the assembly from its top, such as by one or more batter boards. Cementitious material is first poured around the bottom of the anchoring legs attached to the frame members and allowed to set in order to secure the anchoring legs and, in turn, the frame members and the form within the ditch. Then more cementitious material is poured around the form body and allowed to set. Finally the form body is removed to expose the resulting trench and the properly aligned frame members. The removal of the form may be facilitated by a pair of slots extending upwardly into the form body from its bottom surface. By removing an upper portion of the form to access the slots, the form body can be more easily removed from the trench in several pieces.
Drainage channels may also come preformed and assembled on site from a series of discrete drainage channel sections which form and provide a chemical resistant liner in the trench. A first step in installing such a drainage channel is placing the drainage channel sections in an end-to-end relationship at the proper depth below the desired level of the surface. In this regard, a trench may be formed to the desired depth adjacent to the surface for receiving the channel sections. Alternatively, the entire area below the surface may be graded to the desired depth and various subsurface layers can then be placed thereon.
The adjacent ends of two adjoining drainage channel sections may have interlocking end surfaces and may be supported on a single support brick which has been aligned and secured before placement of the drainage channel sections. It is important that the channel sections be supported in such a manner that the channel sections are precisely aligned so as to ensure proper drainage, to permit the grate to seat properly over the open top of the drainage channel, and to prevent adjoining channel sections from being misaligned so as to create a potential trip hazard for people. This proper alignment of the drainage channel sections can be thwarted even if the support bricks are properly aligned if the drainage channel sections and, more particularly, the respective lower surfaces of the drainage channel sections which are seated upon the support bricks are not properly formed in a predetermined aligned relationship. Once the adjoining drainage channel sections have been interlocked, however, the adjacent ends of the sections may be sealed with an adhesive or sealant to prevent leakage.
Once the drainage channel sections are interlocked in an end-to-end relationship, the lower portions of the drainage channel sections are typically encased in concrete so as to secure the channel.
Regardless of the fabrication technique, it is normally desirable to finish the trench with an elongated grate covering its open top in order to prevent people from unwittingly stepping in the open trench, to provide a smooth surface for vehicle travel, and/or to prevent relatively large objects from entering the trench and potentially blocking the flow of liquid therethrough. The grate is generally supported by a pair of spaced apart frame members which are set into and extend from the walls of the concrete trench. In order to stabilize the grate and to prevent the grate from rocking when weight, such as from a passing vehicle, is applied thereto, the frame members must be aligned in a common plane during the pouring and setting of the concrete about the form. If the frame members and, in turn, the grate are not properly aligned, the grate, the frame members and/or the cementitious trench itself may be damaged by the resulting movement of the grate. Accordingly, the alignment of the frame members in the moldable trench forming composition is important.
The problem with the pre-formed drainage channels is the fact that customized molds must be made for each new customer who needs drainage channels of different widths, depths, thicknesses, and slopes. A new custom mold has to be created for each customer based on the particular customer's requirements and on the application for which the drainage channel is going to be used. In many cases each individual customer themselves will have a need for a number of different molds, one for each individual section of the drainage channel that has a different depth or slope in its walls. The cost of building, maintaining, and storing a lot of molds, many of which are only used once, is significant. Therefore it is desirable to control and reduce the number of molds that must be created.